Syrian forces clash with rebels around Aleppo

Free Syrian Army fighters, take their positions as they observe the Syrian army forces base of Wadi al-Deif, at the front line of Maarat al-Nuaman town, in Idlib province, Syria, Tuesday Feb. 26, 2013. Syrian rebels battled government troops near a landmark 12th century mosque in the northern city

/ AP

Free Syrian Army fighters, take their positions as they observe the Syrian army forces base of Wadi al-Deif, at the front line of Maarat al-Nuaman town, in Idlib province, Syria, Tuesday Feb. 26, 2013. Syrian rebels battled government troops near a landmark 12th century mosque in the northern city of Aleppo on Tuesday, while fierce clashes raged around a police academy west of the city, activists said. (AP Photo/Hussein Malla)

Free Syrian Army fighters, take their positions as they observe the Syrian army forces base of Wadi al-Deif, at the front line of Maarat al-Nuaman town, in Idlib province, Syria, Tuesday Feb. 26, 2013. Syrian rebels battled government troops near a landmark 12th century mosque in the northern city of Aleppo on Tuesday, while fierce clashes raged around a police academy west of the city, activists said. (AP Photo/Hussein Malla) (/ AP)

RYAN LUCAS, Associated Press

Syrian warplanes carried out airstrikes on rebels trying to storm a police academy outside Aleppo on Wednesday, while jihadi fighters battled government troops along a key supply road leading to the southeastern part of the city, activists said.

Aleppo, Syria's largest city and former commercial capital, became a key front in the country's civil war after rebels launched an offensive there in July 2012. In months of bloody street fighting, opposition fighters have slowly expanded the turf under their control, although the combat has left much of the city in ruins.

The police academy has recently emerged as a new front in the fight for Aleppo, which is considered a major prize in the conflict. Activists say the government has turned the facility into a military base, using it to shell opposition areas in the countryside as well as rebel-held neighborhoods inside the city.

The Britain-based Syrian Observatory for Human Rights said clashes raged Wednesday around the complex, which is located in the suburb of Khan al-Asal.

"The rebels are still trying to storm the school, but they can't because the regime is carrying out airstrikes and bombarding rebel forces," said Observatory director Rami Abdul-Rahman.

He said at least six rebels were killed Wednesday in the fighting, bringing the three-day death toll to 37 opposition fighters and more than 50 regime troops.

Another key front in the battle for control of Aleppo is the city's international airport. Rebels have been trying for months to seize the facility, and have made headway in recent weeks, overrunning checkpoints and capturing a military base charged with protecting the airport.

The government is desperate to hold onto the facility, which it has used in the past to fly in supplies to its troops bogged down in the city. However, the fighting has forced the government to close the airport to flights and try to send supplies and reinforcements overland.

Most of those reinforcements, including dozens of vehicles and thousands of troops, are now stuck in the city of Safira, southeast of Aleppo, according to Abdul-Rahman. Fighters from Jabhat al-Nusra, an Islamist extremist rebel group that the U.S. has designated a terrorist organization, have cut the road leading from Safira to the airport, and for weeks have battled troops along the road, preventing them from pushing north to the city to link up with government troops there.

The Observatory reported fierce clashes north of Safira on Wednesday, with both sides shelling each other with mortars and artillery.

The rebels have notched a number of strategic victories in recent weeks that appear to mark a shift in momentum in the nearly 2-year-old conflict, which the U.N. says has killed some 70,000 people. Already in control of much of the countryside in the northeast, the rebels have captured the nation's largest hydroelectric dam, a major oil field and two army bases this year.

They have also begun peppering the center of Damascus with mortar shells as part of their effort to bring the fighting from the capital's rebel-held suburbs into the center of the city. On Wednesday, the Observatory said several mortar shells exploded near the military judiciary and near the College of Literature in central Damascus.

Part of the rebel strategy appears to be to try to shatter the sense of normal life that President Bashar Assad's regime has desperately tried to maintain in the capital, which has been insulated from much of the violence ravaging the rest of the country.

The civil war has forced hundreds of thousands of Syrians to flee their homes and seek shelter elsewhere inside the country or abroad.

Jordan said Wednesday new surge in refugees is escaping across the border into the kingdom as fighting intensifies in southern Syria.

Anmar Hmoud, a government spokesman for Syrian refugee affairs, said around 3,000 Syrians a day have crossed into Jordan recently, pushing the total number in the country to nearly 420,000. Some of those coming through unofficial border crossings find shelter in Jordan's Zaatari camp, now home to more than 105,700 refugees. Many more live with Jordanian families.

The U.N. says there are nearly 925,000 displaced Syrians scattered throughout the region.